#164.1 — Config: add `cancel_on_unassign` to Trigger struct

[zeroklaw]

Parent Epic

#164 — Cancel workflow on unassignment

Description

Add a cancel_on_unassign boolean config option to the Trigger struct (alongside allowed_users). When enabled on a github_issue_assigned or gitlab_issue_assigned trigger, receiving an "unassigned" action from the platform webhook cancels the in-flight workflow.

Tasks

• Add cancel_on_unassign: Option<bool> (default None → false) to the Trigger struct in src/workflow.rs
• Add #[serde(default)] annotation so existing configs remain valid
• Update Trigger::validate() to enforce that cancel_on_unassign is only set on github_issue_assigned or gitlab_issue_assigned trigger types (reject on all others with a clear error)
• Update TOML docs/examples

Exit Criteria

• cancel_on_unassign = true accepted on assignment triggers, rejected on others
• Existing workflow TOMLs parse without error
• No dependencies — this is the foundation